1. Field of the Invention
The present invention generally relates to photographic cameras and more particularly, to a lens changeover mechanism for use in a photographic camera, including a master lens and a conversion lens such that said photographic camera is selectively provided with a master lens system constituted by only the master lens and a conversion lens system constituted by both the master lens and the conversion lens, which lens changeover mechanism is adapted to change over either one of the master lens system and the conversion lens system to the other one of the master lens system and the conversion lens system.
2. Description of the Prior Art
Conventionally, there have been proposed several photographic cameras of a type having a built-in wide angle lens (master lens) and a built-in telephoto conversion lens, by which a wide angle photographic picture and a telephoto photographic picture can be selectively taken through manipulation of a lens changeover mechanism. In the known photographic cameras referred to above, it has been so arranged that, in order to change over a wide angle lens system constituted by only the wide angle lens to a telephoto lens system constituted by both the wide angle lens and the telephoto conversion lens, the telephoto conversion lens is brought into alignment with an optical axis of the wide angle lens after the wide angle lens has been advanced through a predetermined distance.
However, the prior art photographic cameras have such inconveniences that the lens changeover mechanism becomes complicated in structure due to displacement of the wide angle lens for focusing adjustment between a retracted position of the wide angle lens at the time of taking the wide angle photographic picture and a projected position of the wide angle lens at the time of taking the telephoto photographic picture, and a large torque is required for manipulating the lens changeover mechanism, while it is difficult to operatively associate the lens changeover mechanism with an autofocus mechanism.